The present invention relates to needle assemblies, and more specifically, to needle assemblies used to enter the arterial system. The present invention also relates to methods of using a needle assembly to maximize the probability of puncturing the artery at its apex and avoiding back sticks.
The prior art is replete with various types of needle assemblies. Most prior art needles do not provide the user with any indication of where the needle tip is actually located. Often times the only signal evidencing arterial penetration is blood on the proximal end of the needle. This imprecise method commonly results in less than optimal needle placement, commonly referred to as "side sticks". A needle assembly providing information about arterial location would enable accurate needle placement thereby reducing the number of side sticks.
The absence of information relating to arterial location also presents problems once the needle has actually penetrated the artery. Because the user may be unaware of the exact moment of needle insertion, the needle is frequently advanced too far. Consequently, the needle may penetrate the back wall of the artery. This problem is commonly known as "back sticks." A needle assembly with a distance limiting feature that would restrict the travel of the needle would eliminate back sticks.
Side sticks and back sticks are particularly problems for procedures that involve catheterization of the artery, such as balloon angioplasty, especially where anticoagulants are present in the blood. The side stick problem is enhanced due to the introducer sheath or catheter being introduced from the wrong angle with respect to the artery. Back sticks allow bleeding out the back of the arterial wall. Of course, since the distance to the back wall of the artery is smaller the further one gets to the side of the artery, side sticks also increase the likelihood of back sticks.
Side sticks also present a problem for wound healing procedures when the catheterization or other procedure is completed. Direct pressure is not as effective when the puncture in the artery is on the side. Also, the various puncture sealing procedures being developed to aid in wound sealing, especially those disclosed in Application Ser. Nos. 08/055,634 and 07/873,955 (now abandoned), both of which are hereby incorporated by reference, are most effective when the vessel puncture is at or near the apex of the vessel.
One device currently on the market is the SmartNeedle.TM. vascular access device sold by the Peripheral Systems Group, An ACS.RTM. company, 1395 Charleston Road, Mountain View, Calif. 94043. The device consists of a detachable probe situated inside the lumen of a standard 18 gauge introducer needle. During use, the probe is connected to a monitor that generates an audio output from a Doppler system located in the probe. The device is advertised as being useful for detecting and precisely locating blood flow within the anatomy. Evidently the audio output helps identify arterial and venous flow, the proximity of the probe to the vessel and when the needle and probe penetrate into the vessel. It is not certain whether the device can help eliminate side sticks and back sticks, but even if so, the device is expensive and requires cumbersome procedures for use.
For these reasons, an inexpensive and easy to use device and method that would decrease side stick and back stick incidents would be a significant improvement in the art.